package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {


    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;


    /**
     * 原生代码解决问题
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
        // 解决缓存穿透
//        Result result = queryByIdForCachePenetration(id);

        // 互斥锁解决缓存击穿
//        Result result = queryWithMutex(id);

        // 逻辑过期解决缓存击穿
        Result result = queryWithLogicalExpire(id);
        return result;
    }

    /**
     * 封装工具类解决问题
     * @param id
     * @return
     */
    public Result queryByIdFromUtils(Long id) {

        //解决缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 互斥锁解决缓存击穿
//        Shop shop = cacheClient.queryWithMutex(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 逻辑过期解决缓存击穿
//        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        return Result.ok(shop);
    }



    private Result queryByIdForCachePenetration(Long id) {
        String key = CACHE_SHOP_KEY + id;
        // 2.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        if ("".equals(shopJson)){
            return Result.fail("店铺不存在！");
        }

        // 3.判断是否存在
        if (Objects.nonNull(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return Result.ok(shop);
        }

        // 4.不存在，根据id查询数据库
        Shop shop = getById(id);
        // 5.不存在，返回错误
        if (shop == null) {

            //redis存空
            stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);

            return Result.fail("店铺不存在！");
        }else {
            // 6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), 30L, TimeUnit.MINUTES);

                    // 7.返回
            return Result.ok(shop);
        }
    }
    private Result queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        // 2.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        if ("".equals(shopJson)){
            return Result.fail("店铺不存在！");
        }

        // 3.判断是否存在
        if (Objects.nonNull(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return Result.ok(shop);
        }

        // 4.实现缓存重建
        // 4.1.获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        Shop shop = null;

            try {
                boolean tryLock = tryLock(lockKey);
                // 4.2.判断是否获取锁成功
                if (!tryLock) {
                    // 4.3.失败，休眠并重试
                    Thread.sleep(50);
                    return queryWithMutex(id);
                }

                // 4.4.成功，根据id查询数据库
                shop = getById(id);
                //4.5 不存在，返回错误
                if (shop == null) {
                    //redis存空
            stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
                }
                //写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);


                    // 6.存在，写入redis

            }catch (Exception e){
                e.printStackTrace();
            }finally {
                //释放互斥锁
                unlock(lockKey);
            }

            return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR =
            Executors.newFixedThreadPool(10);
    public Result queryWithLogicalExpire( Long id ){

        String key = CACHE_SHOP_KEY + id;

        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if ("".equals(shopJson)){
            return Result.fail("店铺不存在！");
        }
        if (Objects.nonNull(shopJson)) {
            // 3.存在，直接返回

            RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
            Object data = redisData.getData();
            Result ok = Result.ok(data);
            return ok;
        }
            //命中
            RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
            Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);

            LocalDateTime expireTime = null;
            if (Objects.nonNull(redisData.getExpireTime())){
             expireTime = redisData.getExpireTime();

            // 4.判断是否过期
            if (expireTime.isAfter(LocalDateTime.now())) {
                // 5.未过期，直接返回
                return Result.ok(shop);
            }
            }
            //为空或者已过期
            // 6.已过期，缓存重建
            // 6.1.获取互斥锁
            String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
            boolean tryLock = tryLock(lockKey);
            if (tryLock){

                CACHE_REBUILD_EXECUTOR.submit(() -> {
                    try {
                        //重建缓存
                        this.saveShop2Redis(id, 20L);
                    }catch (Exception e){
                        e.printStackTrace();
                    }finally {
                        unlock(lockKey);
                    }
                });
            }
            return Result.ok(shop);
        }



    public void saveShop2Redis(Long id,Long expireSeconds){

        // 1.查询店铺数据
        Shop shop = getById(id);
        // 2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        String shopJson = JSONUtil.toJsonStr(redisData);
        // 3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, shopJson);
    }

    @Override
    @Transactional
    public Result updateShop(Shop shop) {
        if (Objects.isNull(shop.getId())){
            return Result.fail("店铺id不能为空");
        }
        Long id = shop.getId();
        // 1.更新数据库
        boolean b = updateById(shop);

        // 2.删除缓存
        String shopKey = CACHE_SHOP_KEY + id;

        Boolean delete = stringRedisTemplate.delete(shopKey);

        return Result.ok(b);
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        if (Objects.isNull(x) || Objects.isNull(y)){
            // 未传入坐标
            Page<Shop> page = query().eq("type_id", typeId).page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }else {
            // 传入坐标
            //去redis中查询
            //计算分页参数
            int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
            int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

            //查询redis，按照距离排序，结果：shopId，distance
            String key = RedisConstants.SHOP_GEO_KEY + typeId;
            GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().
                    search(key, GeoReference.fromCoordinate(x, y), new Distance(5000),
                    RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
            );
            // 4.解析出id
            if (results == null) {
                return Result.ok(Collections.emptyList());
            }
            List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
            if (list.size() <= from) {
                // 没有下一页了，结束
                return Result.ok(Collections.emptyList());
            }

            // 4.1.截取 from ~ end的部分
            List<Long> ids = new ArrayList<>(list.size());
            Map<String, Distance> distanceMap = new HashMap<>(list.size());
            list.stream().skip(from).forEach(result -> {
                // 4.2.获取店铺id
                String shopIdStr = result.getContent().getName();
                ids.add(Long.valueOf(shopIdStr));
                // 4.3.获取距离
                Distance distance = result.getDistance();
                distanceMap.put(shopIdStr, distance);
            });
            // 5.根据id查询Shop
            String idStr = StrUtil.join(",", ids);
            List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
            for (Shop shop : shops) {
                shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
            }
            // 6.返回
            return Result.ok(shops);
        }
    }

    private boolean tryLock(String key) {
    Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
    return BooleanUtil.isTrue(flag);
}

    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }
}
